FMX画图实例

代码下载：

https://download.csdn.net/download/zhujianqiangqq/12394579

代码实例（电脑版、平板版）：

unit Unit1;

interface

uses
  System.SysUtils, System.Types, System.UITypes, System.Classes, System.Variants,
  FMX.Types, FMX.Controls, FMX.Forms, FMX.Graphics, FMX.Dialogs, FMX.Objects,
  FMX.Controls.Presentation, FMX.StdCtrls, FMX.Edit;

type
  TCanvasData = record  //定义绘制数据数组
    //画笔可设置的参数
    PenStartSize: Integer;      //画笔开始大小
    PenMinSize: Integer;        //画笔最小大小
    PenMaxSize: Integer;        //画笔最大大小
    PenMobileBorder: Integer;   //移动界限，超过这个值就改变笔大小值
    PenChangeValue: Integer;    //画笔每次改变的大小
    PenSizeChangeSpeed: Integer;//笔的改变速度，越小改变的速度越快
    //画图用到的参数
    PenCurrentSize: Integer;    //画笔当前大小
    PenLastPoint: TPointF;       //画笔最后的点
    PenMobileDistance: TPointF;  //画笔移动了多少距离
    MouseDownTab:Boolean;       //鼠标按下标记
    Yadd:Integer;
  end;

  TForm1 = class(TForm)
    IMOriginal: TImage;
    IMCanvas: TImage;
    Paint: TPanel;
    operate: TPanel;
    Label1: TLabel;
    Label2: TLabel;
    Label3: TLabel;
    Label4: TLabel;
    Label5: TLabel;
    Label6: TLabel;
    LEPenStartSize: TEdit;
    LEPenMinSize: TEdit;
    LEPenMaxSize: TEdit;
    LEPenMobileBorder: TEdit;
    LEPenChangeValue: TEdit;
    LEPenSizeChangeSpeed: TEdit;
    Timer1: TTimer;
    Button1: TButton;
    procedure IMCanvasMouseDown(Sender: TObject; Button: TMouseButton;
      Shift: TShiftState; X, Y: Single);
    procedure IMCanvasMouseMove(Sender: TObject; Shift: TShiftState; X,
      Y: Single);
    procedure FormCreate(Sender: TObject);
    procedure IMCanvasMouseUp(Sender: TObject; Button: TMouseButton;
      Shift: TShiftState; X, Y: Single);
    procedure Timer1Timer(Sender: TObject);
    procedure LEPenStartSizeChange(Sender: TObject);
    procedure FormResize(Sender: TObject);
    procedure Button1Click(Sender: TObject);
  private
    { Private declarations }
  public
    { Public declarations }
  end;

var
  Form1: TForm1;
  MYCanvasData: TCanvasData;//定义画笔数据变量

implementation
uses
  System.UIConsts;

{$R *.fmx}
{$R *.LgXhdpiPh.fmx ANDROID}

procedure TForm1.LEPenStartSizeChange(Sender: TObject);
begin
  MYCanvasData.PenStartSize := StrToInt(LEPenStartSize.Text);   //开始笔头大小
  MYCanvasData.PenMinSize   := StrToInt(LEPenMinSize.Text);     //最小笔头
  MYCanvasData.PenMaxSize   := StrToInt(LEPenMaxSize.Text);     //最大笔头
  MYCanvasData.PenMobileBorder := StrToInt(LEPenMobileBorder.Text);    //移动距离  超过值时 改变笔头大小
  MYCanvasData.PenChangeValue  := StrToInt(LEPenChangeValue.Text);     //每次大小变动的单位
  MYCanvasData.PenCurrentSize  := StrToInt(LEPenSizeChangeSpeed.Text); //笔头 大小 改变的速度  越小速度越快
end;

procedure TForm1.Button1Click(Sender: TObject);
begin
  IMCanvas.Bitmap := nil;
  IMCanvas.Bitmap.SetSize(Round(IMCanvas.Width), Round(IMCanvas.Height));
end;

procedure TForm1.FormCreate(Sender: TObject);
begin
  IMOriginal.SendToBack;

  LEPenStartSize.Text  := '5';
  LEPenMinSize.Text    := '4';
  LEPenMaxSize.Text    := '10';
  LEPenMobileBorder.Text    := '5';
  LEPenChangeValue.Text     := '1';
  LEPenSizeChangeSpeed.Text := '3';

  MYCanvasData.PenStartSize := 5;
  MYCanvasData.PenMinSize   := 4;
  MYCanvasData.PenMaxSize   := 10;
  MYCanvasData.PenMobileBorder := 5;
  MYCanvasData.PenChangeValue  := 1;
  MYCanvasData.PenSizeChangeSpeed  := 3;

  LEPenStartSize.OnChange := LEPenStartSizeChange;
  LEPenMinSize.OnChange   := LEPenStartSizeChange;
  LEPenMaxSize.OnChange   := LEPenStartSizeChange;
  LEPenMobileBorder.OnChange    := LEPenStartSizeChange;
  LEPenChangeValue.OnChange     := LEPenStartSizeChange;
  LEPenSizeChangeSpeed.OnChange := LEPenStartSizeChange;

  IMCanvas.Bitmap.SetSize(Round(IMCanvas.Width), Round(IMCanvas.Height));
//  IMCanvas.Bitmap.Clear(TAlphaColors.White);
end;

procedure TForm1.FormResize(Sender: TObject);
begin
  IMCanvas.Bitmap.SetSize(Round(IMCanvas.Width), Round(IMCanvas.Height));
end;

procedure TForm1.IMCanvasMouseDown(Sender: TObject; Button: TMouseButton;
  Shift: TShiftState; X, Y: Single);
begin
  case Button of
    TMouseButton.mbLeft:
    begin
      MYCanvasData.PenCurrentSize := MYCanvasData.PenStartSize;
      MYCanvasData.PenMobileDistance.X := -1;
      MYCanvasData.PenLastPoint.X := X;
      MYCanvasData.PenLastPoint.Y := Y;
      //Yadd:=1;
      MYCanvasData.MouseDownTab := True;
    end;
    TMouseButton.mbRight: ;
    TMouseButton.mbMiddle:  ;
  end;
end;

procedure TForm1.IMCanvasMouseMove(Sender: TObject; Shift: TShiftState; X,
  Y: Single);
var
  p1, p2: TPointF;
begin
  Form1.Caption:='当前笔头大小:' + IntToStr(MYCanvasData.PenCurrentSize);
  if MYCanvasData.MouseDownTab then
  begin
    IMCanvas.Bitmap.Canvas.BeginScene;
    IMCanvas.Bitmap.Canvas.Stroke.Thickness := MYCanvasData.PenCurrentSize;
    IMCanvas.Bitmap.Canvas.Stroke.Cap := TStrokeCap.Round;

    p1 := TPointF.Create(MYCanvasData.PenLastPoint.X, MYCanvasData.PenLastPoint.Y);
    p2 := TPointF.Create(X, Y);

    IMCanvas.Bitmap.Canvas.DrawLine(p1, p2, 100);
    IMCanvas.Bitmap.Canvas.EndScene;

    MYCanvasData.PenLastPoint.X := X;
    MYCanvasData.PenLastPoint.Y := Y;
  end;
end;

procedure TForm1.IMCanvasMouseUp(Sender: TObject; Button: TMouseButton;
  Shift: TShiftState; X, Y: Single);
begin
  case Button of
    TMouseButton.mbLeft: MYCanvasData.MouseDownTab := False;
    TMouseButton.mbRight:;
    TMouseButton.mbMiddle:;
  end;
end;

procedure TForm1.Timer1Timer(Sender: TObject);
begin
  if  MYCanvasData.MouseDownTab then
  Begin
    if MYCanvasData.PenMobileDistance.X > -1 then
    begin
      Inc(MYCanvasData.Yadd);
      if (Abs(MYCanvasData.PenMobileDistance.X - MYCanvasData.PenLastPoint.X) < MYCanvasData.PenMobileBorder) and
         (Abs(MYCanvasData.PenMobileDistance.Y - MYCanvasData.PenLastPoint.Y) < MYCanvasData.PenMobileBorder) then
      Begin
        if (MYCanvasData.Yadd >= MYCanvasData.PenSizeChangeSpeed) then
          if (MYCanvasData.PenCurrentSize < MYCanvasData.PenMaxSize) then
          begin
            MYCanvasData.PenCurrentSize := MYCanvasData.PenCurrentSize + MYCanvasData.PenChangeValue;
            MYCanvasData.Yadd:=1;
          end;
      end
      else
      begin
        if (MYCanvasData.Yadd >= MYCanvasData.PenSizeChangeSpeed) then
          if (MYCanvasData.PenCurrentSize > MYCanvasData.PenMinSize) then
          begin
            MYCanvasData.PenCurrentSize := MYCanvasData.PenCurrentSize - MYCanvasData.PenChangeValue;
            MYCanvasData.Yadd := 1;
          end;
      end;
    end;
    MYCanvasData.PenMobileDistance.X := MYCanvasData.PenLastPoint.X;
    MYCanvasData.PenMobileDistance.Y := MYCanvasData.PenLastPoint.Y;
  End;
end;

end.

 代码实例（手机版）：

procedure TForm1.FormCreate(Sender: TObject);
begin
  IMOriginal.SendToBack;

  LEPenStartSize.Text  := '2';//'5';
  LEPenMinSize.Text    := '2';//'4';
  LEPenMaxSize.Text    := '5';//'10';
  LEPenMobileBorder.Text    := '20';//'5';
  LEPenChangeValue.Text     := '1';//'1';
  LEPenSizeChangeSpeed.Text := '1';

  MYCanvasData.PenStartSize := 2;
  MYCanvasData.PenMinSize   := 2;
  MYCanvasData.PenMaxSize   := 5;
  MYCanvasData.PenMobileBorder := 20;//'5';
  MYCanvasData.PenChangeValue  := 1;
  MYCanvasData.PenSizeChangeSpeed  := 1;

  LEPenStartSize.OnChange := LEPenStartSizeChange;
  LEPenMinSize.OnChange   := LEPenStartSizeChange;
  LEPenMaxSize.OnChange   := LEPenStartSizeChange;
  LEPenMobileBorder.OnChange    := LEPenStartSizeChange;
  LEPenChangeValue.OnChange     := LEPenStartSizeChange;
  LEPenSizeChangeSpeed.OnChange := LEPenStartSizeChange;

  IMCanvas.Bitmap.SetSize(Round(IMCanvas.Width), Round(IMCanvas.Height));
//  IMCanvas.Bitmap.Clear(TAlphaColors.White);
end;

procedure TForm1.IMCanvasMouseMove(Sender: TObject; Shift: TShiftState; X,
  Y: Single);
var
  p1, p2: TPointF;
begin
  Form1.Caption:='当前笔头大小:' + FloatToStr(MYCanvasData.PenCurrentSize);
  if MYCanvasData.MouseDownTab then
  begin
    IMCanvas.Bitmap.Canvas.BeginScene;
    IMCanvas.Bitmap.Canvas.Stroke.Thickness := MYCanvasData.PenCurrentSize;
    IMCanvas.Bitmap.Canvas.Stroke.Cap := TStrokeCap.Round;

    p1 := TPointF.Create(MYCanvasData.PenLastPoint.X/3, MYCanvasData.PenLastPoint.Y/3);
    p2 := TPointF.Create(X/3, Y/3);

    IMCanvas.Bitmap.Canvas.DrawLine(p1, p2, 1);
    IMCanvas.Bitmap.Canvas.EndScene;

    MYCanvasData.PenLastPoint.X := X;
    MYCanvasData.PenLastPoint.Y := Y;
  end;
end;